1. Field of the Invention
The present invention relates to a technique that is effective in application to a vehicle equipped with devices, software, and the like, which execute a variety of processes by use of an image picked up in the vehicle.
2. Description of the Related Art
There have hitherto been proposed a variety of devices and applications (hereinafter referred to as “in-vehicle applications”) for offering a service to an occupant by use of an image picked up by a pick-up device installed in a vehicle (hereinafter referred to as “in-vehicle camera”). Examples of techniques used for such in-vehicle applications include the following: a technique of picking up an image of a driver's face for identification, to determine whether the driver is a proper driver or not; a technique of detecting a sight-line direction or a face orientation of a driver from an image, to detect looking aside of the driver; and a technique of detecting the way a driver's eyes are open, from an image, to detect an awake level of the driver.
The balance of a vehicle occupant is susceptible to movement of the vehicle as well as a driving condition. For this reason, a picked-up image is not necessarily suitable for all of the variety of in-vehicle applications thus described. For example, when a vehicle pitches, associated with irregularity of a road surface, the vehicle occupant is also shaken vertically according to the pitching of the vehicle. If an image is picked up in this status, a vertically blurred image of the occupant, an image of the occupant's face with the upper part thereof out of the image region, or the like, might be picked up. Such a low-quality image picked up in the manner thus described has caused a decrease in process accuracy when used for example in identification processing or sight line detection processing.
In order to deal with such a problem, there is a technique in which a shake amount of an automobile is calculated for use in image correction so as to produce an image free of the influence of the shake due to irregularity of a road surface or steering. However, executing such image correction is time consuming. In the case of picking up an image of hardly sufficient quality thus described, therefore, the image has caused a delay in operation of an in-vehicle application.
There is also a technique attempting to solve the problem without the image correction thus described. It is for example possible that quality of a picked-up image is determined by image processing, and when the quality of the picked-up image is determined as insufficient, operation of an in-vehicle application using this image is prohibited. However, this may result in a delay in operation of an in-vehicle application since it takes time to execute the image processing for determining quality of a picked-up image.
There has further been proposed a technique in which, when a vehicle driving speed is not faster than a certain speed, when a steering angle or a yaw rate is not smaller than a prescribed angle or rate, or when a driver is not wearing a seatbelt, the vehicle, since not driving in a normal state, is determined to be in a state where incorrect identification is apt to occur, and thereby a process of identifying the driver's face from an image is prohibited. In such a technique, it is determined whether quality of a picked-up image is sufficient or not, without executing image processing. As for an image of quality determined as insufficient, this image is not corrected, but a process using the image is prohibited. It is thereby possible to avoid a delay caused by image processing or image correction.